1. Field of the Invention
This invention relates to a micro particle image velocimetry, and a particle image-capturing method therefor.
2. Description of the Related Art
Velocity field is one of the most important parameters in analyzing characteristics of fluid motion. In a conventional intrusive method for measuring a velocity field of fluid flow, a probe is dipped in fluid. The intrusion of the probe into the fluid, however, affects the fluid motion, thus causing interference and resulting in an inaccurate measurement. To solve this problem, a non-intrusive method for measuring a velocity field of fluid flow using a particle image velocimetry (PIV) has been proposed.
As the trend toward measurement of microfluids advances, micro-PIVs have been developed. The conventional micro-PIV is based on the setup of the PIV, and includes a double pulse laser, a double exposure mode charge-coupled device (CCD) camera, a microscope, and an analyzer. In a conventional non-intrusive method for measuring a velocity field of fluid flow using the conventional micro-PIV, the double-pulse laser emits light to illuminate fluid and, at the same time, the double exposure mode CCD camera captures two particle images illuminated by the two laser pulses. The analyzer measures a velocity field of the fluid based on a successive pair of images captured by the CCD camera.
Although the aforementioned conventional micro-PIV achieves its intended purpose, the double-pulse laser thereof emits intense and flashing lights, which are harmful to the user's eyes. The intense flashing laser light also causes the particle image to be over-exposed, and hence filters are generally required to reduce the brightness of the images captured by the CCD camera. In addition, the double-pulse laser is expensive and bulky, and incurs high maintenance costs.